1. Field of the Invention
This present invention relates to blade-style electrical terminals and more particularly to a folding blade electrical terminal that facilitates final terminal folding and integral mechanical pull testing while providing a uniform solder fillet when mechanically connected to a work surface.
2. Description of the Prior Art
Electrical terminals must be connected to certain articles of manufacture to allow for the flow of electricity from one medium to a different medium. This is particularly true in instances where the conductive elements are embedded in a non-conductive material, such as glass or dielectric substrate. In, for instance, automotive glass panels having electrical wiring embedded therein for the purpose of defogging the window, electrical terminals must be attached to the glass panels to provide a point of connection for electrical current input and output.
Blade-style terminals are frequently employed in applications requiring the supply of electrical current to conductive elements embedded in non-conductive substrates. For example, when providing electrical current to a defrosting grid on an automotive glass panel, conductive paint is applied to the interior glass surface in a pattern that defines the desired electrical circuit. The blade terminals are then soldered to the heating grid. A lead wire is then connected to the blade terminal using an inexpensive industry-standard box-style terminal which is typically crimped or soldered to the end of the lead wire. Once the box terminal is slid over the blade terminal, the electrical connection is completed. One disadvantage of such a box-style terminal is that it can be accidentally disconnected from the blade terminal. Attempts have been made to cover box terminals with plastic housings having a latch to engage the blade terminal in an effort to prevent the accidental disengagement of the box terminals from the blade terminals. The use of such plastic housings, however, increase the overall height of the assembled terminal connection such that it is unacceptable in many industry applications.
The blade style of terminal has been developed in several design variations to accommodate specific installations. One such variation employs a U-shaped footprint. These terminals have a base having a pair of elongated symmetrical feet that extend outwardly from a center section in a parallel fashion to form a U-shape. The blade typically extends upwardly from the center section at a desired angle relative to the base. This design is further modified through the use of an optional reinforcing xe2x80x9cribxe2x80x9d that is formed in the center of the terminal blade, extending upwardly along the lower portion of the blade. The rib is used to facilitate mechanical pull testing of the terminal""s connection to the work surface without changing the blade""s angle. The disadvantage in using the rib feature is that the terminal blade cannot be bent after the soldering and pull testing steps for final assembly without fracturing the soldered connection. Without the reinforcing rib detail, the terminal blade can be pressed downward to an appropriate angle for final assembly. However, without the rib detail, the terminal cannot be pull-tested to verify the strength of the solder joint without the terminal blade bending and causing the solder joint to fracture.
Another variation of the blade terminal is provided with a narrow xe2x80x9cinlinexe2x80x9d footprint, which is formed by two individual solder pads at the opposite ends of the terminal that are connected to one another by a raised bridge portion. The raised bridge and individual solder pads accommodate the differential of thermal expansion between the base material and the terminal, which would typically weaken the solder joint. However, the inline terminal cannot be pull-tested to verify the strength of the solder joint without bending the bridge portion and causing the solder joint to fracture.
Another disadvantage with either the U-shaped or inline designs is that the pre-clad solder material on their lower surfaces reflows when the terminal is soldered. The solder then typically cools, having formed an irregular solder fillet between the terminal base and the upward projection structure such as the terminal blade or bridge portion. The irregular fillet creates concentrated stress points on the work surface, which is unacceptable in the industry.
Accordingly, what is needed is a blade terminal that facilitates point-of-use final terminal forming and integral mechanical pull testing while having a uniform solder fillet around the base of the terminal.
The folding blade electrical terminal of the present invention is provided with a uniform planar base that, when soldered to a working surface, creates a uniform solder fillet around the base""s perimeter. A terminal blade is operatively connected to one end of the base through an upward projection fold feature and a terminal blade angle hinge feature. These features allow for point-of-use final terminal forming, variable blade angle positioning for assembly, and final assembly angle-setting once the terminal is soldered to the work surface. The terminal blade is formed to receive an industry-standard box-style terminal to complete an electrical connection.
In an alternate embodiment, the folding blade electrical terminal of the present invention is further provided with an interlock that extends upwardly from the base at the opposite end from the terminal blade. Once the box terminal has been secured to the terminal blade and the terminal blade has been folded adjacent the base, the interlock prevents the box terminal from unintentionally sliding off the terminal blade. Other embodiments of the present invention include an optional second terminal blade, and embodiments having varied profile heights.
It is therefore a principal object of the invention to provide a blade terminal that facilitates point-of-use final forming and integral mechanical pull testing while providing a uniform solder fillet around the terminal""s footprint.
Yet another object of the invention is to provide a blade terminal that allows for variable blade angles for assembly.
Still another object of the present invention is to provide a blade terminal that allows for final assembly angle-setting after soldering.
Yet another object of the present invention is to provide a folding blade terminal having an interlock to prevent the unintentional removal of a box terminal that is secured to the terminal blade.
Still another object of the invention is to provide a folding blade terminal that can be formed with a variable profile height.
Yet another object of the present invention is to provide a folding blade terminal that is formed to receive a low profile interlocking cover piece to prevent the unintentional disengagement of a lead wire from the interlock.
These and other objects will be apparent to those skilled in the art.